1. Field of the Invention
The present invention relates in general to a gas chromatograph oven and, more particularly, but not by way of limitation, to a gas chromatograph oven which allows for fast and repetitive sampling of injections.
2. Brief Description of Related Art
Gas chromatography is a means of separating volatile mixture components by selective transport through a column. The column contains a substance called a stationary phase which has a different affinity for each of the mixture components passing through the column. As a result of component interactions with the stationary phase, some are retained on the column longer than others. In a successful separation, components leave the column one at a time. The stationary phase affinity for volatile mixture components is temperature dependent. A common technique used to enhance separation efficiency is to change the stationary phase temperature during the separation. In order to accomplish this, gas chromatograph instruments employ an oven with precise and reproducible temperature control. Highly efficient separations can be achieved in short times by using narrow bore capillary columns and high column heating rates (>1° C./second). Ovens in commercial instruments vary in size, but typically they contain a heating element and fan mounted on an inside wall. The fan circulates the heated air to achieve uniform column heating. After completing a temperature ramp gas chromatographic separation, the oven is typically cooled by opening a door, which allows the hot air to escape. Some ovens can be cooled faster by introducing a coolant such as liquid nitrogen. Faster cooling reduces the time between analyses, which minimizes turnaround times. This is particularly important when gas chromatography is used for process monitoring or for automated analysis of multiple samples with an autosampler.
Gas chromatograph ovens for use in chromatographic analysis have been known for years. Nevertheless, problems related to efficiency and consumption of resources exist. In particular, traditional gas chromatograph ovens are often large devices which require substantial amounts of energy to power. Typically, gas chromatograph ovens include a housing with vents for emitting air, a sealed door, a large fan for circulating air within the housing, and a heating element. These and other moving parts associated with traditional gas chromatograph ovens only serve to increase maintenance costs and process inefficiencies. These detriments also serve to make “fast” chromatography a cumbersome process and also prevent a user from conducting on-site gas chromatography analyses because the size of standard chromatograph ovens make them unsuitable for use in portable devices. Finally, rapid cooling, and thus rapid thermal cycling, is difficult with traditional gas chromatograph ovens due to large amounts of liquid nitrogen being required, which increases the cost of operating the oven.
Thus, a need exists for a gas chromatograph oven which reduces the need for maintenance of the same, enables rapid thermal cycling, and provides for efficacious and/or automated analysis of multiple samples. It is to such an apparatus that the present invention is directed.